1. Field of the Invention
The present invention relates to a rotor for centrifuge used in the field of medicine, pharmaceutical science, genetic engineering, etc., and in particular, to a rotor for centrifugal separation of microplates or a collective unit of microtubes in form of microplates.
2. Description of the Related Art
A conventional type rotor for microplate is described, for example, in Japanese Utility Model Publication 57-934 or Japanese Patent Application 7-316545. A perspective view of the rotor is shown in FIG. 11. In FIG. 11, the rotor comprises a rotor body 21, a bucket 23, and an adapter 25. When it is rotated via a driving shaft of a centrifuge, the bucket 23 is swung, and centrifugal acceleration is applied on a liquid specimen in a microplate, which is supported on the bucket 23 by the adapter 25. The rotor with such arrangement having maximum rotational speed of 2,000 to 6,000 rpm and maximum centrifugal acceleration of 600 to 5,000xc3x97g (gravitational acceleration) is commercially available.
One of the applications, to which the present invention is intended, is the improvement of efficiency in the research activities of DNA and RNA in the field of genetic engineering. In DNA sequencing process in this field, centrifugal separation of DNA as specimen is one of the most important processes. In particular, in the method to collect DNA precipitated by ethanol precipitation processing, which is performed by adding adequate quantity of ethanol to a solution containing DNA, a microtube (test tube) made of plastics of about 0.2 to 2 ml in volume has been used in the past. An angle rotor or a swing rotor compatible with the microtube has been used, and centrifugal separation has been performed at 12,000 rpm (about 10,000xc3x97g) for about 10 minutes. Or, the rotor for microplates as described above has been used for centrifugal separation at 6,000 rpm (about 5,000xc3x97g) for about 30 minutes. In these operations, each of the microtubes must be handled one by one, and this means that very complicated procedure is required. Also, in the former case, because of the limitation of the system for centrifugal separation, processing in one operation has been limited to 48 microtubes at the most. In the latter case, the number of the specimens to be processed is high, but centrifugal acceleration is low, and this means that the separation time as long as 30 minutes is required.
Various types of experiments are now being performed in the field such as examination on human health, research activities of DNA, RNA, etc. or histological culture using the centrifuge. In this respect, there are strong demands on the improvement of efficiency in the process of centrifugal separation, which must be performed in the courses of the examinations, tests, and experiments. The efficiency in the centrifugal separation process can be improved by increasing centrifugal acceleration to be applied on the specimens by increasing the rotational speed and by increasing the number of the samples to be processed at one time.
In some of the conventional type swing rotor for microplates, efficiency can be improved by the use of the microplates, which make it possible to process 96 specimens per one microplate at one time. However, when it is tried to improve the efficiency of centrifugal separation process by increasing the rotational speed, problems of strength arises due to the structure of the rotor, and the rotational speed (centrifugal acceleration) cannot be increased. also, because of the structural feature of the swing rotor, it must have large diameter to improve the efficiency. This causes the problem such as increased windage loss during rotation at high speed. Thus, it is not possible to attain the purpose because the rotational speed and the centrifugal acceleration cannot be increased.
It is an object of the present invention to make it possible to use microplates or a collective unit of microtubes in form of microplates currently in use (hereinafter referred as xe2x80x9cmicroplatexe2x80x9d) under high centrifugal acceleration, to improve efficiency of centrifugal separation process by accommodating more specimens and to reduce the manufacturing cost of the rotor.
The above object can be accomplished by a rotor for centrifuge to apply centrifugal force on a specimen by holding and rotating a box type specimen holder, such as a microplate, with a plurality of recesses for accommodating the specimens, said rotor for centrifuge comprises an outer wall with inner side thereof in parallel to a rotation shaft, and specimen receptacles each extended in direction of the rotation shaft along said outer wall, whereby each of said specimen receptacles is placed in radial direction with respect to the rotation shaft, said box type specimen holder is arranged in each of said specimen receptacles, and there is provided means for preventing said box type specimen holder from toppling or falling down. Also, the present invention provides a rotor for centrifuge to apply centrifugal force on a specimen by holding and rotating a box type specimen holder with a plurality of recesses for accommodating the specimens, said rotor for centrifuge comprises an outer wall with inner side thereof in parallel to a rotation shaft, and specimen receptacles each extended in direction of the rotation shaft along said outer wall, whereby a pad receiving centrifugal force to be applied on said box type specimen holder and having such shape as to engage with the shape of said outer wall is arranged between said box type specimen holder and said inner wall in parallel to said rotation shaft.